No one said it was simple, just possible when you consider all the factors. If it weren't possible like you say, you wouldn't hear estimates in the media like the police estimate the car was traveling in excess of 50 mph.

Even with the recent LIRR incident it wa s estimated that the train was traveling twice the speed limit of five mph. That was partially based on the amount of damage.

That is also how they knew the Hoboken train was traveling even faster because there also was damage to the station.